Meckel's cartilage is essential for mandibular growth because:

 # Meckel's cartilage is essential for mandibular growth because:

A. It is converted into bone 

B. It is a template for bone deposition

C. It is a skeletal unit

D. It is a secondary cartilage

The correct answer is B. It is a template for bone deposition.

Meckel's cartilage is a temporary cartilage structure that forms the basis of the mandibular skeleton in the early embryo. During development, the cartilage acts as a template for the formation of bone, and the mandible grows around it. Meckel's cartilage eventually undergoes resorption, and the mature mandible is formed through a combination of endochondral and intramembranous ossification.

Therefore, the correct answer is B, that Meckel's cartilage is essential for mandibular growth because it serves as a template for bone deposition.

Reference: Proffit, W. R., Fields, H. W. Jr, & Sarver, D. M. (2013). Contemporary Orthodontics. (5th ed.). St. Louis, MO: Mosby/Elsevier. Chapter 4: Growth of the Face and the Jaws.